Device For Actuating A Membrane And A Vehicle Comprising A Device For Actuating A Membrane

ABSTRACT

The invention refers to a device ( 3 ) for actuating a membrane arranged in an opening to a space, and a vehicle having such a device. The membrane ( 1 ) has a first surface ( 1 ′) and a second opposite surface ( 1 ″), and is limited by an edge area. The device includes a first strip ( 5 ) to be attached to the first surface of the membrane in the edge area, and a second strip ( 6 ) to be attached to a surface of a frame portion extending around the opening. An exchanging number ( 8 ) is arranged between and connecting the first strip with the second strip. An actuating member ( 20 ) is arranged to transfer a reciprocating primary movement to the exchanging member converting the primary movement to a reciprocating secondary movement, which has a longer length of stroke than the primary movement and acts on the strips to move towards and away from each other.

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention refers to a device for actuating a membranearranged in an opening to a space, wherein the membrane has a firstsurface and a second opposite surface, and is limited by an edge areaextending around the membrane.

It is known to use such devices for actuating a membrane arranged togenerate sound. The membrane may for instance generate sound in the formof music or any other desired sound. The membrane may also be arrangedto generate sound for attenuating other sounds, so called active soundreduction. Different types of such membranes are known, for instance invarious types of loudspeaker designs, various types of panels such ashat racks in vehicles or windowpanes in vehicles.

U.S. Pat. No. 4,551,849 discloses a sound reducing system arranged tovibrate a panel in a vehicle. In the first place, this document isdirected to the vibration of the hat rack. Also other types of panelsare mentioned, for instance side doors, instrument panels etc.

U.S. Pat. No. 5,812,684 discloses another device for active soundreducing in motor vehicles, in particular for reducing noise fromoutside. The device includes an actuating member in the form of apiezoceramic element which is arranged to vibrate a windowpane of thevehicle. The pane disclosed is supported by an elastomeric stripextending around the pane.

JP-A-06205497 discloses a device for vibrating a rear window of avehicle in order to generate low frequency sound. The device includes anactuating member acting against the window at a substantially centralpoint thereof. The window is supported in the vehicle in a conventionalmanner by means of a rubber strip.

WO96/3513 discloses a device for obtaining acoustic vibrations in amedium by means of a transparent body, for instance a windowpane. In anembodiment, a windowpane is brought to vibrate by means of apiezoelement that is connected to a frame and extends between the frameand the pane proper.

During certain conditions windowpanes are suitable for obtaining soundwith a relatively low frequency. These windowpanes may therebyadvantageously be used as bass loudspeakers included in a musicequipment or sound-generating element in a device for reducing orattenuating sound or noise, i.e. in particular low frequency sound.Windowpanes often have a relatively large surface and are thanks to acurved or double curved design relatively rigid. As actuating membersfor vibrating a membrane or for instance a windowpane it is known to usepiezoelements. One problem with such piezoelements is however that thelength of stroke obtained is too short for bringing a windowpane to amovement with a sufficient amplitude in an efficient manner. An otherimportant precondition for being able to vibrate such a membrane in anefficient manner is that the membrane is supported by a flexible devicepermitting the vibration of the membrane. It is then important that theparts of the actuating device, which are not actuating the pane, have asmall resistance against the movement of the membrane.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an improved device forholding and actuating a membrane. In particular, it is aimed at anactuating device permitting the membrane to move with a small frictionand with a relatively large amplitude. Furthermore, it is aimed at anactuating device also permitting the incorporation of an actuatingmember for achieving a movement of the membrane held by the actuatingdevice.

The object is achieved by the device defined in claim 1. By means ofsuch a device, which includes an exchanging member, an efficientmovement of the membrane may be achieved by means of an activatingmember having a relatively short length of stroke or vibrationamplitude. The exchanging member permits the membrane to move with asignificantly longer length of stroke than the direct movement producedby the activating member and acting on the exchanging member. By meansof this device, it is thus possible to put the membrane into a movementwith such an amplitude that sound having a sufficient loudness may begenerated.

According to an embodiment of the invention, the primary movementextends along a primary axis and the secondary movement extends along asecondary axis forming an angle to the primary axis. Consequently, theactuating member does not need to act in a direction forming the normalto a main extension plane of the membrane, which of course is the mosteffective direction for generating sounds. The possibilities to housethe actuating member in a suitable manner, in for instance a vehicle inwhich the membrane is mounted, are thus improved. Said angle mayadvantageously be substantially perpendicular.

According to a further embodiment of the invention, the exchangingmember includes a rod, which extends between and substantially inparallel to the first strip and the second strip, a plurality ofinclined first link elements, which extend between the rod and the firststrip, and a plurality of inclined second link elements which extendbetween the rod and the second strip. Such a design of the device andthe exchanging member gives a low inner friction, and thus permits themembrane to move easily in parallel with the secondary axis and thenormal to the main extension plane of the membrane. When the primarymovement is transferred to the rod, the link elements will thus rotateso that they are inclined with a larger angle to the rod and therespective strip, and thus displace the strips from each other. In thesame way the strips are again pulled towards each other when the rod ismoved in the opposite direction. The actuating member may suitably bearranged in such a way that it moves the strips to move away from ortowards each other. The link elements may be inclined with an angle thatin a rest state is 10-80°, preferably 30-60°, for instance 35-45°. Theexchange of the exchanging member is determined by the angle ofinclination of the link elements in such a way that the smaller theinclination angle the larger the exchange.

According to a further embodiment of the invention, the actuating memberis arranged to transfer the primary movement of the rod in such a waythat it reciprocates in this longitudinal direction and substantially inparallel with the primary axis, wherein the strips will move towards andaway from each other substantially in parallel with the secondary axis.Advantageously, the first link elements extend substantially in parallelto each other. In the same way also the second link elements extendsubstantially in parallel with each other.

According to a further embodiment of the invention, each link elementhas a first end, which is articulately connected to the rod in aflexible first joint, and a second end, which is articulately connectedto the respective strip in a flexible second joint. The joints areflexible in a first plane including the primary axis and the secondaryaxis. However, the joints are advantageously relatively rigid in a planeforming an angle with said first plane. Advantageously, each linkelement is relatively rigid between the first end and the second end. Insuch a way it is ensured that when the rod is displaced in a direction,the link elements will not be bent but maintain their original shape,wherein a rotation of the link elements takes place at the first andsecond joints in relation to the rod and the respective strip. Each linkelement may include any means for stiffening the link element, forinstance a thickened longitudinal portion or a longitudinal flange.

According to a further embodiment of the invention, each link elementextends from the respective strip towards the rod and towards theactuating member in such a way that the first and second link elementsform an arrow-like configuration pointing towards the actuating member.Advantageously, the device may include a first actuating member and afirst exchanging member, and a second actuating member and a secondexchanging member, wherein the first exchanging member is provided inthe proximity of the second exchanging member in such a way that the twoexchanging members point away from each other towards the respectiveactuating member. By such a configuration, an efficient movement of themembrane is produced when the movements of the two actuating members areco-ordinated to each other. An advantage with such a pair of linkelements is also that the whole horizontal movement of the actuatingmembers is converted to a pure vertical movement of the membrane.

According to a further embodiment of the invention, the actuating memberis provided between the first strip and the second strip. In such a way,the actuating member may be housed in a very space saving manner.Furthermore, the actuating member may advantageously include apiezoelectric element.

According to a further embodiment of the invention, the membrane has asomewhat curved shape. Such a curved or domed shape of the membraneincreases the inherent stiffness of the membrane proper, which improvesits ability to follow the movement initiated by the actuating member andthe exchanging member.

According to a further embodiment of the invention, the device isarranged to create a secondary sound field in said space, wherein thedevice includes a control unit, which is connected to the actuatingmember for controlling the primary movement of the actuating member.Furthermore, the device may be arranged to reduce a primary sound fieldin said space by means of the secondary sound field, wherein the deviceincludes at least one sensor, which senses the primary sound field andis connected to the control unit.

According to a further embodiment of the invention, said space forms thepassenger compartment in a vehicle. The membrane may then advantageouslybe either a front shield and/or a rear window of the vehicle.

The object is also achieved by the vehicle defined in the independentclaim 18.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now to be explained by means of a description ofvarious embodiments and with reference to the drawings attached.

FIG. 1 discloses schematically a side view of a device according to afirst embodiment of the invention.

FIG. 2 discloses a side view of a part of the device in FIG. 1.

FIG. 3 discloses schematically a view in a smaller scale from above of amembrane actuated by four devices according to FIG. 1.

FIG. 4 discloses schematically a side view of a vehicle according to theinvention.

FIG. 5 discloses schematically a rear view of the vehicle in FIG. 3.

FIG. 6 discloses schematically a rear view of an alternative design ofthe vehicle in FIG. 3.

FIG. 7 discloses schematically a side view of a device according to asecond embodiment of the invention.

FIG. 8 discloses schematically a side view of a device according to athird embodiment of the invention.

FIG. 9 discloses schematically a side view of a device according to afourth embodiment of the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

FIGS. 1-3 disclose a membrane 1 which is intended to be provided aroundan opening to a space. The membrane 1 may be formed by a plurality ofvarious elements characterized by a relatively large extension inparallel to a main extension plane x-y, see FIG. 3, and a relativelysmall thickness perpendicular to this extension plane x-y, see FIG. 1.In the following, we will exemplify the invention in connection withmotor vehicles, and especially cars. The invention may however beapplied to many various objects and structures where one desires to holda membrane 1 for generating sound, either in order to reduce orattenuate other sounds or create sound for listening. In addition tocars, the invention may thus be applied to other types of motorvehicles, such as buses and trucks, caravans, aeroplanes, ships andboats etc. The invention is also applicable to stationary structures,for instance different kinds of buildings.

In cars, the membrane 1 may be formed by a plurality of various presentvehicle components or particular components used merely for thispurpose. Examples of present components that can be used for themembrane 1 are the windowpanes of the vehicle, especially the rear paneand/or the front shield. In this case, the membrane 1 is thus providedto cover an opening to the passenger compartment of the vehicle. Themembrane 1 has a first surface 1′ and a second opposite surface 1″. Themembrane 1 is limited by an edge area 2 extending around the membrane 1.

FIGS. 1-3 also disclose a first embodiment of a device 3 for holding andactuating the membrane 1. The device 3 includes a first strip 5, whichis arranged to be attached to the first surface 1′ of the membrane 1 inthe edge area 2. The device 3 also includes a second strip 6, which isarranged to be attached to a surface of a frame portion 7 extendingaround the opening. The frame portion 7 is a part of the object or thestructure to which the device 3 is to be applied, in the exampledisclosed a part of a motor vehicle. The device 3 also includes anexchanging member 8, which is provided between and connects the firststrip 5 and second strip 6. The exchanging member 8 includes a rod 9,which extends between and substantially in parallel with the first strip5 and the second strip 6. Furthermore, the exchanging member 8 includesa plurality of inclined first link elements 10, which extend between therod 9 and the first strip 5, and a plurality of inclined second linkelements 11, which extend between the rod 9 and the second strip 6. Thefirst link elements 10 extend substantially in parallel to each other.Also the second link elements 11 extend substantially in parallel toeach other.

Each link element 10, 11 has a first end, which is articulatelyconnected to the rod 9 in a flexible first joint 12, and a second end,which is articulately connected to the respective strip 5, 6 in aflexible second joint 13, see FIG. 2. The flexible joints 12, 13 may beobtained for instance by giving the link elements 10, 11 at the ends orin the proximity of the ends a thinner thickness of material thanbetween the ends. Between the ends, the link elements 10, 11 arerelatively rigid. The rigidity may be increased by letting the linkelements 10, 11 include one or several longitudinal ribs or longitudinalflanges. The strips 5, 6, the rod 9 and the link elements 10, 11 have arelatively short extension in a plane x-z, which is perpendicular to themain extension plane x-y, but a relatively large extension perpendicularto this plane, compare FIG. 3. As appears from FIGS. 1 and 2, each linkelement 10, 11 extends from the respective strip 5, 6 towards the rod 9in such a way that the link elements 10, 11 together with the rod 9 forman arrow-like configuration.

By the proposed design of the exchanging member 8, it is thus possibledisplace the membrane 1 towards and away from the frame portion 7. Ifthe rod 9 performs a reciprocating primary movement along a primary axisx, which extends substantially in parallel with the plane x-y, the linkelements 10, 11 will rotate around the joints 12, 13 so that the firststrip 5 is displaced in relation to the second strip 6 by areciprocating secondary movement in parallel with a secondary axis zwhich is substantially perpendicular to the extension plane x-y. Thesecondary axis z is substantially perpendicular to the primary axis x.

The exchanging member 8 may be manufactured in various ways. Accordingto an embodiment of the exchanging member 8, i.e. the strips 5, 6, thelink elements 10, 11 and the rod 9, may be manufactured in one singlepiece of any suitable material, for instance a mould injected plasticmaterial. The strips 5, 6, the link elements 10, 11 and the rod 9 mayalso be manufactured separately from each other and thereafter joined tothe structure disclosed, for instance by gluing or melting. In this casethe different elements may be manufactured of any suitable plasticmaterial, metal material, or any composite material, for instance glassfibre laminate.

The device 3 also includes an actuating member 20, which is arranged totransfer said reciprocating primary movement to the exchanging member 8by displacing the rod 9. The actuating member 20 may advantageouslyinclude a piezoelectric element 21, which is in engagement with andconnected to the rod 9 in such a way that pushing and pulling forces maybe transferred from the actuating member 20 to the rod 9 at the sametime as the rod 9 may be displaced in parallel to the axis z in relationto the actuating member 20. The actuating member 20 may thus be arrangedto displace the rod 9 substantially in parallel to the primary axis x ina reciprocating primary movement. This primary movement is transferredvia the link elements 10, 11 to the first strip 5, which thus moves witha reciprocating secondary movement in parallel with the secondary axis zin relation to the second strip 6 and the frame portion 7.

The link elements 10, 11 are inclined by an angle a in relation to therod 9 and the strips 5, 6. Depending on the size of the angle a, theexchange of the exchanging member 8 may be determined. A more acuteangle a between the link elements 10, 11, and the rod 9 and the strips5, 6, respectively, gives a higher exchange than a less acute angle a.The angle a may in a rest state be for instance 10-80°, preferably30-60°, for instance 30-45°. An angle a of 45° with regard to the twostrips 5, 6 and the rod 9 gives a total exchange between the primarymovement and the secondary movement of 1:2.

In the first embodiment disclosed in FIG. 1, the device 3 includes afirst actuating member 20 and a first exchanging member 8 pointing tothe left in the figure, and a second actuating member 20 and a secondexchanging member 8 pointing to the right in the figure. The twoexchanging members 8 are provided adjacent to each other, and thus pointaway from each other towards the respective actuating member 20.Furthermore, the strips 5 and 6 are connected to each other viatransversal portions 24, 25, which may be an integrated part of theexchanging member 8 and extend between the strips 5, 6 immediatelyoutside the actuating member 20. In such a way, the device will be kepttogether by the strips 5 and 6. A change of the length of thepiezoelectric element 21 in parallel with the primary axis x will resultin a displacement of the strips in relation to each other in parallelwith the secondary axis z. By such a configuration, an efficientmovement of the membrane 1 may thus be obtained when the movements ofthe two actuating members 20 are co-ordinated to each other. FIG. 3discloses an embodiment where the membrane 1 is held in its edge area byfour devices 3 of the type disclosed in FIGS. 1 and 2. By four suchdevices 3, it may be ensured that the whole membrane 1 is put intomovement.

The device 3 may advantageously be used for vibrating a membrane 1 forgenerating sound. This application of the device 3 may be used invehicles, which is schematically illustrated in FIGS. 4-6. In theapplication disclosed, the device 3 is intended to reduce the soundlevel in the passenger compartment 31 of the vehicle 30. In thisapplication, the device 3 is arranged to hold the rear pane 32 of thevehicle 30, which thus forms the membrane. The rear pane 32 has asomewhat domed or curved shape, which is advantageous since it increasesthe stiffness of the rear pane 32. However, the rear pane 32 extendsalong a main extension plane x-y that is substantially perpendicular tothe secondary axis z.

In the embodiments disclosed in FIGS. 4-6, the device 3 is arranged tocreate a secondary sound field in the passenger compartment 31 of thevehicle 30 in particular for reducing a primary sound field in thepassenger compartment 31. The device 3 includes a schematicallydisclosed control unit 33 and a number of sensors 34, which sense theprimary sound field and are connected to the control unit 33. Thecontrol unit 33 is connected to the actuating member 20 for controllingthe primary movement of the actuating member 20 with regard to theprimary sound field. One example of how the control unit 33 may bedesigned and co-operate with sensors and sound influencing members,which in this case is formed by the membrane 1 or the rear pane 32, ismore closely disclosed in WO01/41123.

FIG. 5 discloses an embodiment where the rear pane is held by one orseveral devices 3, which extend along the edge area 2 along a lower edgeof the rear pane 32. The upper edge and the side edges of the rear pane32 are attached to the vehicle 30 in such a way that the rear pane mayrotate around a rotary axis extending in parallel with the upper edge.

FIG. 6 discloses another embodiment where the rear pane 32 is held bydevices 3 extending along parts of the edge area 2 at the lower edge,the upper edge and the side edges.

FIG. 7 discloses a second embodiment of the device 3 for holding andactuating the membrane 1. In all disclosed embodiments, elements havingthe same function have been provided with the same reference signs. Thesecond embodiment differs from the first embodiment in that the strips 5and 6 are not connected to each other by means of any transversalportions. The actuating member 20 instead includes a holder 27 for thepiezoelectric element 21. The holder 27 is attached to the second strip6. The piezoelectric element 21 is connected to the rod by means of aschematically disclosed roller bearing 28, which permits transfer ofpushing and pulling forces from the actuating member 20 to the rod 9 atthe same time as the rod 9 may be displaced in parallel with the axis zin relation to the actuating member 20. The actuating member 20 willthus also in this case displace the rod 9 substantially in parallel withthe primary axis x in a reciprocating primary movement. This primarymovement is transferred via the link elements 10, 11 to the first strip5 which thus reciprocates with a secondary movement in parallel with thesecondary axis z in relation to the second strip 6 and the frame portion7.

FIG. 8 discloses a third embodiment of the device 3 for holding andactuating the membrane 1. The third embodiment differs from the firstembodiments in that the device includes only one exchanging member 8 andone actuating member 20. In this case, a schematically disclosed guidemember 41 is provided for guiding the movement of the strips 5, 6 insuch a way that it only may be displaced in parallel with the secondaryaxis z. The guide member 41 thus prevents the strips 5, 6 from moving inparallel with the plane x-y in relation to each other.

FIG. 9 discloses a fourth embodiment of the device 3 for holding andactuating the membrane 1. The fourth embodiment differs from the thirdembodiment in that the device includes only one actuating member 20 andonly one exchanging member 8 with only the first link elements 10. Inthis case there is in addition to the guide member 41 also aschematically disclosed support member 42 for supporting the rod 9. Thesupport member 42 permits the displacement of the rod in parallel withthe plane x-y but prevents the rod 9 from being displaced in parallelwith the secondary axis z. It is to be noted that the guide member 41and the support member 42 may be designed in many various ways.

The invention is not limited to the embodiments disclosed but may bevaried and modified within a scope of the following claims.

1-79. (canceled)
 80. A system for generating sound in a vehicle, saidsystem comprising: a membrane mounted at a space in a vehicle equippedwith said system, said membrane comprising a window pane and having acurved shape and an inherent stiffness; a device for actuating saidmembrane, said device comprising an exchanging member having arelatively short length of stroke; whereby said exchanging member allowssaid membrane to move with a significantly longer length of stroke.